test(e2e): browser suite for the flows the server tests cannot see

Playwright under e2e/, its own npm project so Meteor never sees the dependency
(.meteorignore keeps the directory out of the bundle — a config file at the app
root is otherwise eagerly loaded into the server and crashes it).

Covers what the phase asked for: sign up / log in, creating a zone from the map
and watching the union get painted on /subscriptions and /zones, removing it
again, commenting on a fire, and switching language. The zone spec is the flow
that froze staging on 2026-07-30 — it passes only if the server is still
answering DDP while the union is recomputed.

docker-compose.e2e.yml is a throwaway stack (Mongo on tmpfs, no named volume) so
the destructive seeds cannot be pointed at anything real by accident;
playwright.config.js refuses to start against the staging or production domains.

i18n.spec.js leaves a test.fixme on a real bug found while writing it: the
language chosen in the profile does not survive a page reload.

e2e/.gitignore

@@ -0,0 +1,3 @@
+node_modules/
+playwright-report/
+test-results/